Process for decomposing fats or oils into fatty acids and glycerin



Patented Mar. 29, 1927 All BERT S. RICHARDSON AND CLINTON V. CONLEY, OF CIIICINNATI, OHIO, ASSIGNOBS TO THE PROCTER & GAMBLE COMPANY, OF CINCINNATI, OHIO, A CORPORATION OF OHIO.

PROCESS FOR DECOMPOSING FATS OR OILS INTO FATTY ACIDS AND GLYCERIN.

N0 Drawing.

The objects of our invention are to decrease the amount of impurities present in the fatty acids obtained by the decomposition of fats or oils and also to cheapen the operation by the substitution of less expensive reagents for those previously used in the process.

The nature of our invention can be best understood by reference to the prior operation which our new process is intended to replace. It has been common practice to carry out the reaction between fats or oils and water to form fatty acids and glycerln, a re action known as the hydrolysis of fats or oils, by bringing together the reacting substances, at a suitable temperature and with provision for mixing either by steam or by mechanical stirring, in the presence of relatively small quantities of mineral acids and of organic sulfonic acids known as saponi; fiers, emulsifiers, splitting agents, etc.

The saponifiers used in past practice have consisted in large part of fatty-aromatic-sulfonic acids, which are prepared by the action of sulfuric acid on a mixture of unsatured fatty acids, e. g, oleic acid, and aromatic hydrocarbons, e. g, benzene, naphthalene, or cymene. Also, there have been used as saponifiers sulfonic acids of petroleum hydrocarbons of high molecular weight, comparable with the high molecular weight of the fatty-aromatic-sulfonic acids. For example, Petrofi, describing a process for the preparation of sulfonic acids of petroleum oils, states that all these have a molecular weight higher than 250. Of correspond ingly high molecular weight are the proposed saponifiers prepared by the sulfonation of high boiling hydrocarbons from lignite tar, coal tar, peat tar, and bituminous minerals, such as anthracene oil or solar oil of specific gravity 0.8621.

It has been commonly supposed that the sulfonic acids of aromatic hydrocarbons such as benzene, or naphthalene, or their simple derivatives of relatively low molecular weight, such as toluene, or cymene, are not active as saponifiers. We have found, however, that the sulfonic acids of the simple aromatic hydrocarbons, such as occur in nature or are readily obtained by the thermal decomposition of naturally occurring products, are in fact active as saponifiers,

Applieation 'filcd March 13, 1922. Serial No. 543,514.

even when such sulfonic acids have molecular weights well below 250. Even benzene sulfonic acid has an :u'ipreciable activity, although the activity of the sulfonic acids of aromatic hydrocarbons containing no aliphatic side chains (for example, benzene or naphthalene) is relatively slight. The activity of the saponifier is greatly increased if the molecule of the aromatic hydrocarbon contains one or more aliphatic side chains. Thus the sulfonic acids of toluene and of the Xylenes are considerably more active than benzene sulfonic acid, while the sulfonic acids of the higher boiling liquid hydrocarbons obtained from coal tar solvent naphtha are still more active. Also the sulfonic acid of cymene, a hydrocarbon occurring in spruce turpentine, is quite active.

As compared with the saponifiers hitherto employed, our saponifiers have the advan tage of greater purity and of lower cost.

Mineral acids, e. g., sulfuric acid, when used in conjunction with our saponifiers produce a more rapid reaction and in this respect are of considerable advantage. However, such mineral acids are not essential and have the disadvantage of producing fatty acids of darker color.

During hydrolysis the saponiticrs hitherto employed dissolve chiefly in the fatty layer, even though possessing a considerable degree of water solubility in the absence of fatty matter. On the contrary, our saponifiers dissolve chiefly in the aqueous layer and .wholly so if the concentration of mineral acid is not greater than 4% of sulphuric acid. Since, moreover, the rate of hydrolysis of fats increases rapidly with increasing concentration of water soluble saponifiers, the relative proportion of water and saponifier used in our process is particularly important. It is desirable at all times to restrict the quantity of water present to the minimum amount necessary for the reaction. In other respects, the operation of hydrolyzing fats with our saponifiers does not differ in any essential from the Well known and widely practiced piperation as carried out with other saponiers.

EwampZea-IOO parts of tallow, 2% parts of cymene sulfonic acid, and 20 parts of water were heated to 100 0., and

mechanically agitated. In five hours the free ftty acid increased from 5.5% to 7 5.4% ofthe total fatty acid content of the tallow. 100 parts of similar tallow, treated as above except for the addition of one part of 66 B. sulfuric acid, contained free atty acids to the extent of 80.7% of the total fatty acids after five hours, but the product was more darkened. The fats or oils hydrolyzed in this way can be used directly for purposes which require a high free fatty acid content. If higher free fatty acid content is desired, the reaction can he continued with the addition of more water and the partially hydrolyzed fatcan then he giyen a second saponification treatment, in which case the, resulting water lfayer is used for the first treatment of fresh Having thus described our inventioin' what we claim as new and desire to secure by Letters Patent, is 2- 1. The process of. decompqsing fats or oils into fatty acids and glycerin by reaction with Water, which consists of heating and agitating the rea'ction' substances in the presence of arornatic sulfonic acids of molecular weight less than 250' without the use of oleic or similar fatty acid, substantially as described.

2. The process of decomposing fats or oils into fatty acids and glycerinby reaction with water, which consists of heating and agitating the reactin substances in the presence of aromatic sulfonic acids f llltllecular weight less thanQSO without the use of oleicorsirnilar fatty acid, to ether with sulphuric acid, substantiall as described;

ALBERT S. RfflHARDSON. CLINTON V. CONLEY.

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